here using the error function (erf). The first term, the long-range interaction,
is assigned to wave function theory, whereas the second term, the short-range interaction, is assigned
to DFT. Contrary to conventional DFT the fictitious reference (Kohn-Sham) system is no longer non-interacting and can not be solved exactly,
so that the hierarchy of approximate wave function methods must be invoked. MP2-srDFT has been implemented in DIRAC by Ossama Kullie
and Trond Saue [Kullie2011].